Methods for improved die bonding

ABSTRACT

Methods for improved die bonding. In some embodiments, a method includes applying hot air to a die. The method also includes placing the die on a substrate after applying the hot air to the die. The method further includes waiting a predefined bonding period in order to establish a bond between the die and the substrate.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. Patent Application No.15/394,609, filed Dec. 29, 2016, entitled “METHOD AND DEVICE FORIMPROVED DIE BONDING,” which claims priority to U.S. Provisional PatentApplication No. 62/272,914, filed Dec. 30, 2015, entitled “METHOD ANDDEVICE FOR IMPROVED DIE BONDING.” The contents of each of theabove-referenced application(s) are hereby expressly incorporated byreference herein in their entireties for all purposes.

BACKGROUND Field

The present disclosure relates to systems and methods of manufacturingchips or integrated circuits (ICs).

Description of Related Art

During a manufacturing process, chips and/or integrated circuits (ICs),semiconductor die are often bonded to a substrate or package with anadhesive material. Bonding the chips and/or integrate circuits to asubstrate/package with an adhesive material may be referred to herein asa “die bonding process.”

SUMMARY

In some implementations, the present disclosure relates to a bondingdevice comprising. The bonding device includes a heating elementconfigured to heat air. The bonding device also includes an applicationelement having a plurality of holes configured to apply the heated airto a die, the application element is characterized by an arrangement ofthe plurality of holes that satisfies one or more directionalitycriteria. The bonding device further includes a controller configured tocontrol the heating element and to set the temperature of the heated airexpelled through the plurality of holes of the application element inorder to satisfy one or more bonding criteria.

In some embodiments, the bonding device further includes an air blowerconfigured to expel the heated air through the plurality of holes of theapplication element.

In some embodiments, the controller is configured to control the airblower and to set the pressure of the heated air expelled through theplurality of holes of the application element in order to satisfy theone or more bonding criteria.

In some embodiments, the controller is configured to control the airblower and to set the velocity of the heated air expelled through theplurality of holes of the application element in order to satisfy theone or more bonding criteria.

In some embodiments, the application element includes a temperaturesensor that provides the temperature of the heated air expelled throughthe plurality of holes of the application element to satisfy the one ormore bonding criteria.

In some embodiments, the application element includes a pressure sensorthat provides the pressure of the heated air expelled through theplurality of holes of the application element to the controller.

In some embodiments, the application element includes a velocity sensorthat provides the velocity of the heated air expelled through theplurality of holes of the application element to the controller.

In some embodiments, the one or more directionality criteria aresatisfied when the angle of each of the plurality of holes is apredetermined angle.

In some embodiments, the one or more directionality criteria aresatisfied when the plurality of holes have a predetermined focal point.

In some embodiments, the one or more bonding criteria are satisfied whena time to bond the die to a substrate is less than a predefined timeperiod.

In some embodiments, the one or more bonding criteria are satisfied whena yield of die bonded to substrates exceeds a predefined threshold.

In some embodiments, a count of the plurality of holes satisfies apredetermined count.

In some embodiments, the application element is circular.

In some implementations, the present disclosure relates to a method. Themethod includes applying hot air to a die. The method also includesplacing the die on a substrate after applying the hot air to the die.The method further includes waiting a predefined bonding period in orderto establish a bond between the die and the substrate.

In some embodiments, the method further includes picking up the dieprior to applying the hot air to the die.

In some embodiments, the die is picked up from a wafer, the waferincludes a plurality of die.

In some embodiments, the method further includes applying an adhesive tothe substrate before placing the die on the substrate.

In some embodiments, the temperature of the hot air satisfies atemperature criterion.

In some embodiments, the pressure of the hot air satisfies a pressurecriterion.

In some embodiments, the velocity of the hot air satisfies a velocitycriterion.

In some embodiments, a length of time that the hot air is applied to thedie satisfies a predefined application period.

In some embodiments, applying the hot air to the die includespositioning the die a predetermined distance from the source of the hotair.

In some implementations, the present disclosure relates to a bondingsystem. The bonding system includes a heating element configured to heatair. The bonding system also includes an application element having aplurality of holes configured to apply the heated air to a die, theapplication element is characterized by an arrangement of the pluralityof holes that satisfies one or more directionality criteria, theapplication element including one or more sensors for collectingfeedback information associated with at least one of the temperature,pressure, and velocity of the heated air expelled through the pluralityof holes of the application element. The bonding system further includesan air blower configured to expel the heated air through the pluralityof holes of the application element. The bonding system further includesa controller configured to control the heating element and the airblower based on the feedback information from the one or more sensors,the controller sets at least one of the temperature, pressure, andvelocity of the heated air expelled through the plurality of holes ofthe application element in order to satisfy one or more bondingcriteria.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart representation of a method of die bonding, inaccordance with some embodiments.

FIG. 2 is a flowchart representation of a method of die bonding, inaccordance with some embodiments.

FIG. 3 is a block diagram of a bonding device, in accordance with someembodiments.

FIG. 4A is a schematic diagram of a first view the application element,in accordance with some embodiments.

FIG. 4B is a schematic diagram of a second view the application element,in accordance with some embodiments.

FIG. 5 shows example performance data, in accordance with someembodiments.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the claimed invention.

When manufacturing chips or integrated circuits (ICs), semiconductor dieare often bonded to a substrate or package with an adhesive material(sometimes also herein referred to as the “die bonding process”). Insome situations, low yields are observed for film applications of thedie bonding process due to the lack of adherence of film adhesives. Onesolution to this problem is to apply heat after placing a die on thesubstrate. This solution, however, is unsatisfactory as it leads toquality control failures, and, in turn, decreased units-per-hour (UPH).

The present disclosure may help solve and/or mitigate the adherenceproblem while maintaining satisfactory UPH.

FIG. 1 is a flowchart representation of a method 100 of die bonding inaccordance with some implementations. While pertinent features areshown, those of ordinary skill in the art will appreciate from thepresent disclosure that various other features have not been illustratedfor the sake of brevity and so as not to obscure more pertinent aspectsof the example implementations disclosed herein. To that end, briefly,in some circumstances, the method 100 includes: picking up a die;placing the die on a substrate; and applying heat to bond the die to thesubstrate.

To that end, as represented by block 1-1, the method 100 includespicking up a die. For example, a die is picked up from a wafer, whichincludes a plurality of die, by a pick-up tip of a manufacturingmachine.

As represented by block 1-2, the method 100 includes placing the die ona substrate. For example, the substrate is associated with a chip or anIC. In some embodiments, an adhesive (e.g., an epoxy) is applied to alocation on the substrate that is associated with the die prior toplacing the die on the substrate.

As represented by block 1-3, the method 100 includes applying heat tobond the die to the substrate. In some embodiments, hot air (e.g.,between 100° C. and 300° C.) is applied to the combination of the dieand the substrate in order to cure or set the adhesive so that a properbond is established between the die and the substrate.

FIG. 2 is a flowchart representation of another method 200 of improveddie bonding in accordance with some implementations. While pertinentfeatures are shown, those of ordinary skill in the art will appreciatefrom the present disclosure that various other features have not beenillustrated for the sake of brevity and so as not to obscure morepertinent aspects of the example implementations disclosed herein. Tothat end, briefly, in some circumstances, the method 200 includes:picking up a die; applying heat to the die; placing the die on asubstrate; and bonding the die to the substrate at room temperature.

To that end, as represented by block 2-1, the method 200 includespicking up a die. For example, a die is picked up from a wafer, whichincludes a plurality of die, by a pick-up tip of a manufacturing machine(e.g., a robotic arm).

As represented by block 2-2, the method 200 includes applying heat tothe die. In some embodiments, hot air (e.g., (e.g., between 100° C. and300° C.) is applied to the die by an application element (e.g., theapplication element 306 in FIGS. 3 and 4A-4B). In some embodiments, thetemperature of the hot air satisfies a temperature criterion (e.g., 110to 120° C.). In some embodiments, the pressure of the hot air satisfiesa pressure criterion (e.g., 0.1 to 0.2 mPa). In some embodiments, thevelocity of the hot air satisfies a velocity criterion (e.g., 10 to10000 cm³ /second). In some embodiments, the die is positioned apredetermined distance from the application element by the pick-up tip(e.g., 0.5 to 10 cm). In some embodiments, a length of time that the hotair is applied to the die satisfies a predefined application period(e.g., 0.1 to 60 seconds).

As represented by block 2-3, the method 200 includes placing the die ona substrate. For example, the substrate is associated with a chip or anIC. In some embodiments, an adhesive (e.g., an epoxy) is applied to alocation on the substrate that is associated with the die prior toplacing the die on the substrate.

As represented by block 2-4, the method 200 includes bonding the die tothe substrate at room temperature. In some embodiments, the pre-heateddie is allowed to bond with the substrate at room temperature so that aproper bond is established between the die and the substrate. In someembodiments, a bond between the die and the substrate is established bywaiting a predefined bonding period (e.g., 1 minute to 24 hours) priorto further handling of the chip or IC.

FIG. 3 is a block diagram of a bonding device 300 in accordance withsome embodiments. While pertinent features are shown, those of ordinaryskill in the art will appreciate from the present disclosure thatvarious other features have not been illustrated for the sake of brevityand so as not to obscure more pertinent aspects of the exampleimplementations disclosed herein. To that end, the bonding device 300includes: a heater element 302, an air blower 304, a controller 306, andan application element 308 with one or more sensors 310.

In some embodiments, the heater element 302 is configured to intake airat room temperature and heat the air to a temperature set by thecontroller 306. In some embodiments, the air blower 304 is configured toforce the air heated by the heater element 302 through a plurality ofholes of the application element 308. In some embodiments, the airblower 304 forces the heated air through the plurality of holes of theapplication element 308 at a pressure and velocity set by the controller306. According to some embodiments, the heater element 302 and the airblower 304 are separate components as shown in FIG. 3. In someembodiments, the functionalities of the heater element 302 and the airblower 304 are consolidated in a single component (e.g., an air handler)capable of heating and moving air.

In some embodiments, the controller 306 is configured to control theheater element 302 and the air blower 304 based on feedback informationfrom the heater element 302 (e.g., temperature) and the air blower 304(e.g., pressure and velocity), and the one or more sensors 310associated with the application element 310 (e.g., temperature, pressureand velocity) in order to satisfy one or more bonding criteria. In someembodiments, the one or more bonding criteria are satisfied when a timeto bond the die to a substrate is less than a predefined time period(e.g., 60 minutes). In some embodiments, wherein the one or more bondingcriteria are satisfied when a yield of die bonded to substrates exceedsa predefined threshold (e.g., 99%).

In some embodiments, the controller 306 sets the heater element 302(e.g., controls the input voltage or provides a temperature level) suchthat the temperature of the hot air expelled through the plurality ofholes of the application element 308 (e.g., as measured by the one ormore sensors 310) satisfies a temperature criterion (e.g., 110 to 120°C.). In some embodiments, the controller 306 sets the air blower 304(e.g., controls the input voltage or provides a pressure level) suchthat the pressure of the hot air expelled through the plurality of holesof the application element 308 (e.g., as measured by the one or moresensors 310) satisfies a pressure criterion (e.g., 0.1 to 0.2 mPa). Insome embodiments, the controller 306 sets the air blower 304 (e.g.,controls the input voltage or provides a velocity magnitude) such thatthe velocity of the hot air expelled through the plurality of holes ofthe application element 308 (e.g., as measured by the one or moresensors 310) satisfies a velocity criterion (e.g., 10 to 10000 cm³/second).

In some embodiments, the application element 308 includes a plurality ofholes (e.g., as shown in FIGS. 4A-4B). In some embodiments, a count ofthe plurality of holes satisfies a predetermined count (e.g., 16). Insome embodiments, the application element 308 is a circular, annulus- orring-shape as shown in FIGS. 3 and 4A-4B. In some embodiments, theapplication element 308 includes an intake coupled to the air blower 302as shown in FIGS. 4A-4B. In some embodiments, the application element308 also includes one or more sensors 310 (e.g., a temperature sensor, apressure sensor, a velocity sensor, etc.). In some embodiments, theapplication element 308 further includes a heat lamp (e.g., a bakelight) as shown in FIGS. 4A-4B.

In some embodiments, the application element 308 is characterized by anarrangement of the plurality of holes that satisfies one or moredirectionality criteria. In some embodiments, as will be described inmore detail with respect to FIGS. 4A-4B, the one or more directionalitycriteria are satisfied when the angle of each of the plurality of holesis a predetermined angle (e.g., 45°). In some embodiments, as will bedescribed in more detail with respect to FIGS. 4A-4B, the one or moredirectionality criteria are satisfied when the plurality of holes have apredetermined focal point.

FIG. 4A is a schematic diagram of a first view the application element308 in accordance with some embodiments. While pertinent features areshown, those of ordinary skill in the art will appreciate from thepresent disclosure that various other features have not been illustratedfor the sake of brevity and so as not to obscure more pertinent aspectsof the example implementations disclosed herein. To that end, theapplication element 308 includes a plurality of holes includingrepresentative hole 406, an intake 408, and an optional heat lamp 410.

As shown in FIG. 4A, a die 404 is positioned above the applicationelement 408 by a pick-up tip 402 of a manufacturing machine (e.g., arobotic arm). According to some embodiments, the plurality of holes ofthe application element 308 have a focal point 405 as shown in FIG. 4A.For example, the focal point 405 is associated with a centroid of thedie 404. In some embodiments, the one or more directionality criteriaare satisfied when the plurality of holes have a predetermined focalpoint (e.g., the focal point 405). In some embodiments, the applicationelement 308 is a circular, annulus-shape with the plurality of holes onthe inner perimeter and a heat lamp 310 in its center.

FIG. 4B is a schematic diagram of a second view the application element308 in accordance with some embodiments. In FIG. 4B, the elements of theapplication element 308 are similar to and adapted from those discussedabove with reference to FIG. 4A. Elements common to FIGS. 4A and 4Binclude common reference numbers, and only the differences between FIGS.4A and 4B are described herein for the sake of brevity. According tosome embodiments, the die 404 is positioned a distance 412 (e.g., 0.5 to10 cm) from the application element 308. In some embodiments, each ofthe plurality of holes of the application element 308 have an angle 415.In some embodiments, the one or more directionality criteria aresatisfied when the angle of each of the plurality of holes is apredetermined angle (e.g., the angle 415).

FIG. 5 shows example performance data for the method 200 of improved diebonding in FIG. 2 in accordance with some embodiments. According to someembodiments, the performance data shows the number and percentage offailures for 1340 chips or ICs produced according to the “hot air” diebonding process described in method 200 and a “no heat” control diebonding process. As shown in FIG. 5, performance data is broken down bythe type of failures such as “no PA (power amplifier),” “no spacer, “SW(switch) moved on spacer,” “SW broken on spacer,” “no SW on PCB (printedcircuit board),” “SW moved on PCB,” and “double SW on PCB.” FIG. 5 alsoshows illustrative examples of some of the aforementioned failure types.As shown in FIG. 5, the performance data shows the yield for the “noheat” control die bonding process (e.g., 54.48%) and for the “hot air”die bonding process (e.g., 99.55%). As such, the “hot air” die bondingprocess described in method 200 has a very high yield as compared to thecontrol die bonding process the and die bonding process described inmethod 100.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” The word “coupled”, as generally usedherein, refers to two or more elements that may be either directlyconnected, or connected by way of one or more intermediate elements.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Wherethe context permits, words in the above Detailed Description using thesingular or plural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list, and anycombination of the items in the list.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese processes or blocks may be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks may instead be performedin parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

While some implementations of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the disclosure. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the disclosure.

What is claimed is:
 1. A method comprising: applying hot air to a die;placing the die on a substrate after applying the hot air to the die;and waiting a predefined bonding period in order to establish a bondbetween the die and the substrate.
 2. The method of claim 1 furthercomprising picking up the die prior to applying the hot air to the die.3. The method of claim 2 wherein the die is picked up from a wafer, thewafer includes a plurality of die.
 4. The method of claim 1 furthercomprising applying an adhesive to the substrate before placing the dieon the substrate.
 5. The method of claim 1 wherein the temperature ofthe hot air satisfies a temperature criterion.
 6. The method of claim 1wherein the pressure of the hot air satisfies a pressure criterion. 7.The method of claim 1 wherein the velocity of the hot air satisfies avelocity criterion.
 8. The method of claim 1 wherein a length of timethat the hot air is applied to the die satisfies a predefinedapplication period.
 9. The method of claim 1 wherein applying the hotair to the die includes positioning the die a predetermined distancefrom the source of the hot air.